This is something we rarely do, testing our detectors.
It was just that we had a bit of rain and didn't want to move about on wet tracks so I placed a few nuggets out on a clean patch of smooth dirt.
The biggest was (the biggest we found) 5.5g that I placed in a zip bag and covered with a bucket of wet soil at a depth of about 125mm.
The others, a 0.12g, a 0.3g and a 1g all lying in the surface.
We used the GPX6000 fitted with the Coiltek 10"x5" and the original 11" mono.
The GPZ7000 with the NF 12" and the original 14" coil.
The GPX4500 with Woody's frequency modification fitted with the original 11" mono and the Coiltek 14" Elite mono.
The ground was wet but not heavily mineralized. The standout of our very basic tests were the two Coiltek coils. Both these coils have exceptional detection at edge of the coil. The small Coiltek coil could detect the 0.12g nugget 40mm before it reached the target. The big 14" Coiltek on the GPX4500 detected it as well but it had to be within about 25mm above the tiny nugget.
All coils detected all the nuggets with the GPZ7000 with the standard 14" coil being the winner overall but not the best in all situations. The NF was disappointing and was removed from service. It's edge detection is virtually non-existent having to pass about 30-40mm over the target before detection. That makes it useless in anything but open country an even then it's like a small coil in a large housing.
The GPX6000 with the 11" mono performed well in all situations but couldn't match the small nugget performance of the little Coiltek coil or the large nugget detection of the GPZ7000 and the GPX4500. This 5.5g nugget was under a pile of muddy dirt from the bottom of a nearby gully.
We never used the SDC2300's at all on this trip. All these detectors did a great job in their original configuration but the GPX6000 performance on small gold was enhanced by fitting the little Coiltek coil, the GPX4500 performance was greatly improved by fitting the Coiltek 14" Elite coil and the GPZ7000 performed best in it's original form but don't ever ask me to try to carry one around. The GPX4500 with the Coiltek coil is still the winner on bigger gold at depth but looses out on anything smaller.
This was not a comprehensive test, just a bit of time spent to keep us busy on a wet morning.